The 33-year-old, who had one year left on his deal, was told at the end of last season that he was free to talk to other clubs as the Blues look to cut their wage bill.

"The club would like to take this opportunity to thank Marlon for his magnificent service to Blues over the last two seasons and wish him well for the next chapter of his career," read a statement on Birmingham's official website.

King joined Birmingham on a free transfer from Coventry City in June 2011.